Japanese Patent No. 3975918 (Patent Literature 1) discloses an antenna device included in a mobile electronic apparatus for use in RFID systems. The antenna device of Patent Literature 1 includes an asymmetrical coil where two positions are opposed to each other with the center of a coil winding area therebetween and the winding pitch varies between the two positions. On a side having a larger winding pitch, a magnetic body is disposed on the back of a main surface opposed to an IC card; on a side having a smaller winding pitch, a magnetic body is disposed on the main surface opposed to the IC card.